The present invention relates to sights for archery bows which are adjustable according to the range of the target, and in particular to a bow sight having a rangefinding means which automatically adjusts the sight in accordance with the range determined.
As is well known among bow hunters, in order for the arrow to hit the desired target the arrow must be aimed above the target when released, due to the influence of gravity on the arrow in flight. All other factors being equal, the farther away the target, the higher above the target the arrow must be aimed, within the practical range of the given bow and arrow combination. It is a common practice to provide sight pins spaced vertically with respect to each other and fixed to the midportion of the bow. The placement and spacing between the pins is calibrated to the particular bow and its recommended weight arrow, such that each sight pin corresponds to a particular target range, such as 20 yards, 30 yards, 40 yards, etc. The hunter upon selecting his target must estimate from his experience the range of the target, then sight the target on the proper sight pin which corresponds to his range estimate. This system, while a distinct improvement over "eyeballing" the sighting without benefit of reference sights, suffers from inherent inaccuracy due to the requirement of estimating the range, and even when the range has been estimated correctly, there is a great likelihood of sighting on the wrong pin in one's haste to get the shot off before the target escapes.
A known improvement over the above described sighting system involves single adjustable sight pin which is vertically movable the pin being set according to vertically spaced indicia on the midportion of the bow each of which corresponds to a particular range. This system eliminates the possibility of error by sighting on the wrong pin, as there is only one, but retains the inaccuracy inherent in estimating the range in the first instance.
There has therefore arisen a need for an adjustable bow sight incorporating a rangefinding feature for accurately determining the range, and automatically setting the sight pin in the proper location for the range determined.